Semiconductor devices and methods of manufacture thereof having guard ring structure

ABSTRACT

In some embodiments, an integrated circuit (IC) device includes a substrate having a first functional region, a second functional region and a third functional region. The IC device also includes a plurality of dielectric layers over the substrate, a first guard ring in the plurality of dielectric layers and around the first functional region, and a second guard ring in the plurality of dielectric layers and around the second functional region. The second guard ring is separate from the first guard ring, and the third functional region is free of a guard ring. The IC device further includes a seal ring in the plurality of dielectric layers. The seal ring encircles the first and the second guard rings, and is separate from the first and the second guard rings.

This application is a continuation of U.S. patent application Ser. No. 13/689,385, filed on Nov. 29, 2012, entitled “Semiconductor Devices and Methods of Manufacture Thereof,” which application is incorporated herein by reference in its entirety.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically manufactured by providing a workpiece, forming various material layers over the workpiece, and patterning the material layers using lithography to form integrated circuits. The semiconductor industry continues to improve the integration density of various electronic components of integrated circuits, i.e., transistors, diodes, resistors, capacitors, etc., by continual reductions in minimum feature size, which allow more components to be integrated into a given area.

Conductive materials such as metals or semiconductors are used in semiconductor devices for making electrical connections for the integrated circuits. For many years, aluminum was used as a metal for conductive materials for electrical connections, and silicon dioxide was used as an insulator. However, as devices are decreased in size, the materials for conductors and insulators have changed in order to improve device performance. Copper is now often used as a conductive material for interconnects in some applications. Low dielectric constant (k) materials and extra-low k (ELK) materials have begun to be implemented in some designs for insulating materials of interconnects.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a top view of a semiconductor device in accordance with some embodiments, wherein a guard ring is formed around a functional region of an integrated circuit;

FIG. 2 is a cross-sectional view of a portion of the semiconductor device shown in FIG. 1;

FIG. 3 is a top view of a semiconductor device in accordance with other embodiments, wherein a guard ring is formed around each functional region of an integrated circuit;

FIG. 4 is a perspective view of the semiconductor device shown in FIG. 3;

FIG. 5 is a top view of a semiconductor device in accordance with other embodiments, wherein a guard ring is formed around each functional region of an integrated circuit;

FIG. 6 is a perspective view of the semiconductor device shown in FIG. 5;

FIG. 7 is a perspective view of a semiconductor device in accordance with some embodiments, wherein a guard ring is formed around some functional regions of an integrated circuit;

FIG. 8 is a perspective view of a guard ring in accordance with some embodiments, wherein the guard ring is continuous;

FIG. 9 is a perspective view of a guard ring in accordance with other embodiments, wherein the guard ring is discontinuous;

FIG. 10 is a perspective view of two guard rings in accordance with some embodiments, wherein a circuit routing line is routed through the discontinuous regions of the guard rings;

FIGS. 11 and 12 are cross-sectional views of a portion of a guard ring in accordance with some embodiments;

FIG. 13 is a cross-sectional view of a seal ring that is disposed around a plurality of guard rings of a semiconductor device in accordance with some embodiments;

FIG. 14 is a flow chart of a method of manufacturing a semiconductor device in accordance with some embodiments; and

FIG. 15 illustrates a top view of a workpiece with a plurality of integrated circuits formed thereon, in accordance with some embodiments.

Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of some of the embodiments of the present disclosure are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the disclosure, and do not limit the scope of the disclosure.

Some embodiments of the present disclosure are related to semiconductor devices and methods of manufacture thereof. Novel guard rings for multi-function integrated circuits will be described herein.

Referring first to FIG. 1, a top view of a semiconductor device 100 in accordance with some embodiments is shown, wherein a guard ring 106 a is formed around a functional region 104 a of an integrated circuit. The semiconductor device 100 includes a workpiece 102. The workpiece 102 may include a semiconductor substrate comprising silicon or other semiconductor materials and may be covered by an insulating layer, for example. The workpiece 102 may also include other active components or circuits, not shown. The workpiece 102 may comprise silicon oxide over single-crystal silicon, for example. The workpiece 102 may include semiconductor elements such as transistors, diodes, etc. Compound semiconductors, GaAs, InP, Si/Ge, or SiC, as examples, may be used in place of silicon. The workpiece 102 may comprise a silicon-on-insulator (SOI) or a germanium-on-insulator (GOI) substrate, as examples.

Active regions are formed in and/or over the workpiece 102 in functional regions 104 a and 104 b of the semiconductor device 100. The active regions may comprise transistors such as transistor 116 shown in FIG. 2, logic devices, memory devices, or other types of circuitry. Only two functional regions 104 a and 104 b are shown in FIG. 1; however, in accordance with some embodiments, three or more functional regions 104 are formed on a single integrated circuit, to be described further herein.

The guard ring 106 a is formed around a perimeter of functional region 104 a. The guard ring 106 a is formed in the upper material layers of the semiconductor device 100 in some embodiments. The guard ring 106 a is formed in the metallization layers M₁, V₁, and M_(N) (see FIG. 2) of the semiconductor device 100, for example, to be described further herein. The guard ring 106 a is formed in every metallization layer M₁, V₁, and M_(N) of the semiconductor device 100 in some embodiments.

Referring again to FIG. 1, a seal ring 108 is formed around a perimeter of the integrated circuit. The seal ring 108 is formed around the guard ring 106 a disposed around the functional region 104 a. The seal ring 108 is also around the functional region 104 b. In some embodiments, the seal ring 108 is formed in the same material layer or layers that the guard ring 106 a is formed in.

In some embodiments, a guard ring 106 a is formed on only one functional region 104 a, or on only some functional regions 104 a of the semiconductor device 100. In other embodiments, a guard ring 106 a is formed on all of the functional regions 104 a and 104 b of the semiconductor device 100. For example, a guard ring 106 b is shown in phantom disposed around the perimeter of the functional region 104 b in FIG. 1.

FIG. 2 is a cross-sectional view of a portion of the semiconductor device 100 shown in FIG. 1. A cross-sectional view of the guard ring 106 a and a portion of the functional region 104 a are shown. An example of an active region in the functional region 104 a is illustrated wherein the active region comprises a transistor 116. Alternatively, the functional region 104 a may comprise other types of circuitry. The transistor 116 includes source and drain regions 124 formed within the workpiece 102 that are defined at the edges by shallow trench isolation (STI) regions 118. The transistor 116 includes a gate dielectric 122 formed over the workpiece 102 between the source and drain regions 124, and a gate 120 disposed over the gate dielectric 122.

The semiconductor device 100 includes a contact layer CO that includes contacts 114 formed in an insulating material 115 that is disposed over the transistor 116 and other active devices of the functional region 104 a, not shown. The contacts 114 make electrical contact with the gate 120 of the transistor 116. Other contacts 114 may also be formed, such as contacts for the source and drain regions 124 of the transistor 116, not shown. A plurality of metallization layers M₁, V₁, and M_(N) is formed over the contact layer CO, where conductive lines 110′ and vias 112″ are formed that provide electrical connections for the functional region 104 a.

The guard ring 106 a is formed in the metallization layers M₁, V₁, and M_(N) of the semiconductor device 100. The guard ring 106 a comprises a conductive line 110 formed in metallization layer M₁, conductive vias 112 or one or more via bars 112′ formed in metallization layer V₁ coupled to a top surface of the conductive line 110 in metallization layer M₁, and a conductive line 110 formed in metallization layer M_(N) that is coupled to the conductive vias 112 or one or more via bars 112′. The conductive line 110 in metallization layer M₁, conductive vias 112 or one or more via bars 112′, and conductive line 110 formed in metallization layer M_(N) are formed in insulating material layers 132 a, 132 b, and 132 c, respectively. The insulating material layers 132 a, 132 b, and 132 c are also referred to herein as a material layer 130.

The conductive lines 110 of the guard ring 106 a comprise Cu, a Cu alloy, other metals, or multiple layers or combinations thereof, for example. The conductive lines 110 of the guard ring 106 a comprise a width in the cross-sectional view comprising dimension d₁. Dimension d₁ comprises about 0.1 μm or greater in some embodiments, as an example. In some embodiments, dimension d₁ comprises about 1.5 μm, as another example. Alternatively, dimension d₁ may comprise other values, and the conductive lines 110 may comprise other materials. The conductive lines 110 are continuous in the example shown. Alternatively, the conductive lines 110 may be discontinuous, to be described further herein.

The conductive vias 112 or via bars 112′ of the guard ring 106 a also comprise Cu, a Cu alloy, other metals, or multiple layers or combinations thereof, for example. Alternatively, the conductive vias 112 or via bars 112′ may comprise other materials. The conductive vias 112 or via bars 112′ comprise a width in the cross-sectional view comprising dimension d₂. Dimension d₂ comprises about 0.05 μm or greater in some embodiments, as an example. Alternatively, dimension d₂ may comprise other values. The conductive vias 112 may comprise an array of a plurality of vias 112 disposed between the conductive lines 110 in metallization layers M₁ and M_(N), or a continuous or discontinuous via bar 112′ disposed between the conductive lines 110 in metallization layers M₁ and M_(N).

The guard ring 106 a is spaced apart from the perimeter of the functional region 104 a by a dimension d₃ comprising about 0.1 μm or less in some embodiments, as an example. In other embodiments, the guard ring 106 may be spaced apart from the perimeter of the functional region 104 a by other dimensions.

One or more of the insulating material layers 132 a, 132 b, and/or 132 c may comprise a low dielectric constant (k) material having a dielectric constant or k value less than the dielectric constant of silicon dioxide, which is about 3.9, in some embodiments. In other embodiments, one or more of the insulating material layers 132 a, 132 b, and/or 132 c may comprise an extra low k (ELK) material having a dielectric constant or k value of about 2.5 or less, as another example. The insulating material layers 132 a, 132 b, and/or 132 c may comprise a dielectric film such as a Black Diamond™ (BD) film, fluorinated silicon glass (FSG), or other materials having a thickness of about 70 to 210 nm, as examples. Alternatively, the insulating material layers 132 a, 132 b, and/or 132 c may comprise other materials and dimensions. Some of these materials have a low structural strength, and the guard ring 106 a disposed proximate the perimeter of the functional region 104 a advantageously provides increased structural support and robustness for the semiconductor device 100. The guard ring 106 a also prevents or reduces the likelihood of delamination of the insulating materials 132 a, 132 b, and/or 132 c, for example.

To manufacture the semiconductor device 100, the workpiece 102 provided, and the active regions are formed in the functional regions 104 a and 104 b, such as transistors 116. Contacts 114 are formed in an insulating material 115 that is formed over the workpiece 102 and active regions. The metallization layers M₁, V₁, and M_(N) are formed using subtractive or damascene techniques. Two adjacent metallization layers V₁/M_(N) may be simultaneously formed using a dual damascene technique in some embodiments, as another example. The guard ring 106 a is advantageously formed simultaneously with the formation of the conductive lines 110′ and vias 112″ of the functional regions 104 a in some embodiments. In other embodiments, the guard ring 106 a may alternatively be formed using a separate manufacturing or lithography process step.

FIG. 3 is a top view of a semiconductor device 100 in accordance with other embodiments, wherein a guard ring 106 is formed around each functional region 104 of an integrated circuit. FIG. 4 is a perspective view of the semiconductor device 100 shown in FIG. 3. A seal ring 108 is formed around the perimeter of the semiconductor device 100, e.g., around the guard rings 106 disposed around the functional regions 104.

The functional regions 104 comprise substantially the same size and shape in the embodiment shown in FIGS. 3 and 4. The functional regions 104 may comprise a plurality of memory devices or other types of devices having similar or the same functions, as an example. Alternatively, the functional regions 104 may comprise different functions.

In FIG. 4, for simplicity, conductive lines and vias formed in the metallization layers M₁, V₁, and/or M_(N) over the functional regions 104 are not shown; however, conductive lines and vias may be formed in the same metallization layers M₁, V₁, and/or M_(N) over the functional regions 104 that the guard rings 106 are formed in, in some embodiments. Every functional region 104 and guard ring 106 is not labeled in FIG. 4 (or in FIGS. 5 and 6), also to simplify the drawings.

FIG. 5 is a top view of a semiconductor device 100 in accordance with other embodiments, wherein a guard ring 106 is formed around each functional region 104 of an integrated circuit. FIG. 6 is a perspective view of the semiconductor device 100 shown in FIG. 5. The functional regions 104 comprise different shapes and sizes in the embodiment shown. The functional regions 104 may also comprise different or substantially the same functions. The functional regions 104 may comprise various functions, circuitry, or modules, for example, depending on the application and type of semiconductor device 100.

The semiconductor device 100 comprises a single integrated circuit including the functional regions 104, wherein the integrated circuit is fabricated on a workpiece 102 comprising a semiconductor wafer. A plurality of the integrated circuits are manufactured on the workpiece 102 (as shown in FIG. 15) and are later singulated into a plurality of semiconductor devices 100 comprising systems-on-a chip (SOCs), each including a plurality of functional regions 104 in some embodiments, for example.

FIG. 7 is a perspective view of a semiconductor device 100 in accordance with some embodiments, wherein a guard ring 106 a, 106 a, 106 c, and 106 d is formed around some functional regions 104 a, 104 b, 104 c, and 104 d, respectively, of an integrated circuit. A guard ring is not formed on other functional regions 104. The guard rings 106 a, 106 b, 106 c, and 106 d can be included in the semiconductor device 100 around predetermined functional regions 104 a, 104 b, 104 c, and 104 d, for example. The guard rings 106 a, 106 b, 106 c, and 106 d can be included in the semiconductor device 100 around specific functional regions 104 a, 104 b, 104 c, and 104 d that need and benefit from increased robustness, for example. The guard rings 106 a, 106 b, 106 c, and 106 d can also, or alternatively, be included in the semiconductor device 100 around functional regions 104 a, 104 b, 104 c, and 104 d where there is sufficient area for the guard rings 106 a, 106 b, 106 c, and 106 d, as another example.

FIG. 8 is a perspective view of a guard ring 106 of a semiconductor device 100 in accordance with some embodiments, wherein the guard ring 106 is continuous. Conductive lines 110 formed in metallization layers M₁ and M_(N) each comprise a continuous conductive line 100. A single continuous via bar 112′ comprises a continuous conductive line formed in metallization layer V₁. The continuous via bar 112′ has a smaller width than conductive lines 110. The continuous guard ring 106 shown in FIG. 8 is fully sealed and provides a large improvement in robustness of the semiconductor device 100 proximate the guard ring 106. A continuous guard ring 106 may be formed around the perimeter of one or more functional circuits 104 of a semiconductor device 100 in accordance with some embodiments of the present disclosure.

FIG. 9 is a perspective view of a guard ring 106 of a semiconductor device 100 in accordance with other embodiments, wherein the guard ring 106 is discontinuous. The conductive lines 110 in metallization layers M₁ and M_(N) are discontinuous, and the via bars 112′ in metallization layer V₁ are also discontinuous in some embodiments. Metallization layer V₁ may include one or more vias 112 disposed between the via bars 112′. Alternatively, only one of the conductive lines 110 in metallization layer M₁ or M_(N) may be discontinuous. The discontinuous regions 134 of the guard ring 106 allow for circuit routing; e.g., to another area or region of the semiconductor device 100.

FIG. 10 is a perspective view of two guard rings 106 a and 106 b in accordance with some embodiments, wherein a circuit routing line 136 is routed through the discontinuous regions 134 of the guard rings 106 a and 106 b. The guard rings 106 a and 106 b are each discontinuous on one side in the embodiment shown. Both conductive lines 110 a and 110 b in the metallization layers M₁ and M_(N) of the guard rings 106 a and 106 b, respectively, may be discontinuous, or only one conductive line 110 a in metallization layer M₁ (or M_(N), not shown) of the guard rings 106 a and 106 b, respectively, may be discontinuous, as shown in phantom in FIG. 10. The via bars 112 a′ and 112 b′ of the guard rings 106 a and 106 b, respectively, are both discontinuous. One end 138 a of the circuit routing line 136 may be electrically coupled to functional region 104 a, and another end 138 b of the circuit routing line 136 may be electrically coupled to functional region 104 b, to provide electrical connection between the functional regions 104 a and 104 b, in some embodiments. Alternatively, the discontinuous regions 134 of the guard rings 106 a and 106 b may be used to provide electrical connection of the functional regions 104 a or 104 b to other regions, contact pads, or input/output regions of the semiconductor device 100, for example, not shown.

FIGS. 11 and 12 are cross-sectional views of a portion of a guard ring 106 of a semiconductor device 100 in accordance with some embodiments. Vias 112 or via bars 112′ are formed in metallization layers V₁ through V_(N-1), and conductive lines 110 are formed in metallization layers M₁ through M_(N). Passivation layers 144 a and 144 b (see FIG. 12) are disposed over the top metallization layer V_(N-1)/M_(N) formed within an insulating material layer 132. In FIG. 11, some of the conductive lines 110 are continuous, and other conductive lines 110 are discontinuous and include a discontinuous region 134.

In FIG. 12, a circuit routing line 136 is formed in a discontinuous region 134 of the guard ring 106. The circuit routing line 136 provides electrical connection from the functional region 104 to an exterior region 142 of the functional region 104. The circuit routing line 136 is adapted to output a signal 140 from the functional region 104 of the semiconductor device 100 to the exterior region 142 of the functional region 104, for example. For simplicity, not all of the conductive lines 110, vias 112 or via bars 112′, or insulating material layers 132 are labeled in FIGS. 11 and 12.

FIG. 13 is a cross-sectional view of a more detailed view of a seal ring 108 that is disposed around a plurality of guard rings 106 (not shown in FIG. 13; see FIG. 12) of a semiconductor device 100 in accordance with some embodiments. The seal ring 108 is formed proximate scribe lines 148 of the semiconductor device 100. Portions of the seal ring 108 are formed in the same material layers M₁ through M_(N) and V₁ through V_(N-1) that portions of the guard rings 106 (see FIG. 12) are formed in. The seal ring 108 comprises two concentric rings 150 b and 150 a of conductive material, wherein the larger ring 150 a includes a conductive material 146 disposed proximate a top surface thereof. The seal ring 108 reduces or prevents cracking during die sawing and prevents damage from moisture in the finished integrated circuit. The smaller ring 150 b comprises a sacrificial component in some embodiments that is destroyed in the sawing process, and the larger ring 150 a is left remaining in the structure, for example. Alternatively, the seal ring 108 may comprise a single large ring 150 a and the smaller ring 150 b may not be included, for example, not shown.

FIG. 14 is a flow chart 160 of a method of manufacturing a semiconductor device in accordance with some embodiments. In step 162, a first functional region of an integrated circuit is formed over a workpiece. In step 164, a second functional region of the integrated circuit is formed over the workpiece. In step 166, a guard ring is formed around the first functional region of the integrated circuit in a material layer disposed over the first functional region and the second functional region of the integrated circuit.

Some embodiments of the present disclosure include methods of manufacturing semiconductor devices. Other embodiments include semiconductor devices 100 that include the novel guard rings 106, 106 a, 106 b, 106 c, and 106 d described herein.

Advantages of some embodiments of the disclosure include providing novel guard rings 106, 106 a, 106 b, 106 c, and 106 d that reduce or prevent delamination of insulating material layers 132, 132 a, 132 b, and 132 c of semiconductor devices 100 and strengthen the overall structure of the integrated circuits, resulting in integrated circuits with reinforced strength. Stress in the insulating material layers 132, 132 a, 132 b, and 132 c is reduced due to the conductive material tower structures (e.g., comprised of the conductive lines 110 and vias 112 and/or via bars 112′) of the guard rings 106, 106 a, 106 b, 106 c, and 106 d, resulting in delamination protection for the insulating material layers 132, 132 a, 132 b, and 132 c of the material layer 130 the guard rings 106, 106 a, 106 b, 106 c, and 106 d are formed in. The guard rings 106, 106 a, 106 b, 106 c, and 106 d are particularly beneficial in providing robustness-enhanced structures for insulating material layers 132, 132 a, 132 b, and 132 c of the material layer 130 in embodiments wherein the insulating material layers 132, 132 a, 132 b, and 132 c comprise ELK materials, for example. The novel guard rings 106, 106 a, 106 b, 106 c, and 106 d provide improved mechanical support within the semiconductor device 100 (e.g., of the integrated circuit).

The guard rings 106, 106 a, 106 b, 106 c, and 106 d also provide noise reduction or prevention, due to the conductive materials of the conductive lines 110 and vias 112 and/or via bars 112′. The guard rings 106, 106 a, 106 b, 106 c, and 106 d also function as shields, preventing noise from affecting the functional regions 104, 104 a, 104 b, 104 c, and 104 d and/or preventing the functional regions 104, 104 a, 104 b, 104 c, and 104 d from emitting noise that may deleteriously affect other functional regions 104, 104 a, 104 b, 104 c, and 104 d and/or devices external to the semiconductor devices 100, as examples. Functional regions 104, 104 a, 104 b, 104 c, and 104 d can be protected from noise from other functional regions 104, 104 a, 104 b, 104 c, and 104 d in a single integrated circuit by implementing the novel guard rings 106, 106 a, 106 b, 106 c, and 106 d described herein.

No additional lithography masks or processes are required to include the guard rings 106, 106 a, 106 b, 106 c, and 106 d in back-end-of-line (BEOL) processes and structures in some embodiments; rather, existing photolithography masks and processes used to form conductive lines 110′ and vias 112″ for the functional regions 104 a (see FIG. 2) can be modified to form the novel guard rings 106, 106 a, 106 b, 106 c, and 106 d described herein. Furthermore, the novel guard ring 106, 106 a, 106 b, 106 c, and 106 d structures and designs are easily implementable in manufacturing process flows.

In accordance with some embodiments of the present disclosure, an integrated circuit (IC) device includes a substrate having a first functional region, a second functional region and a third functional region. The IC device also includes a plurality of dielectric layers over the substrate, a first guard ring in the plurality of dielectric layers and around the first functional region, and a second guard ring in the plurality of dielectric layers and around the second functional region. The second guard ring is separate from the first guard ring, and the third functional region is free of a guard ring. The IC device further includes a seal ring in the plurality of dielectric layers. The seal ring encircles the first and the second guard rings, and is separate from the first and the second guard rings.

In accordance with other embodiments, a method of manufacturing a semiconductor device includes forming a plurality of integrated circuits (ICs) over a substrate, forming a plurality of seal rings in dielectric layers over the plurality of ICs, each of the plurality of seal rings surrounding a respective one of the plurality of ICs individually, and forming a first guard ring in the dielectric layers, the first guard ring being inside a first seal ring of the plurality of seal rings and around a first functional region of a first IC of the plurality of the ICs. The method further includes forming a second guard ring in the dielectric layers, the second guard ring being inside the first seal ring and around a second functional region of the first IC. The second guard ring is separate from the first guard ring, a third functional region of the first IC does not have a guard ring around it, and the first seal ring is separate from the first guard ring and the second guard ring.

In accordance with yet other embodiments, a method of manufacturing a semiconductor device includes forming an integrated circuit (IC) die over a workpiece, forming a first guard ring in a material layer over the IC die, the first guard ring encircling a first functional region of the IC die, and forming a second guard ring in the material layer, the second guard ring encircling a second functional region of the IC die. The second guard ring is spaced apart from the first guard ring, and a third functional region of the IC die is without a guard ring. The method further includes forming a seal ring in the material layer and along a perimeter of the IC die, the seal ring encircles the IC die individually and is spaced apart from the first guard ring and the second guard ring.

Although some embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. For example, it will be readily understood by those skilled in the art that many of the features, functions, processes, and materials described herein may be varied while remaining within the scope of the present disclosure. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

What is claimed is:
 1. An integrated circuit (IC) device comprising: a substrate having a first functional region, a second functional region and a third functional region; a plurality of dielectric layers over the substrate; a first guard ring in the plurality of dielectric layers and around the first functional region; a second guard ring in the plurality of dielectric layers and around the second functional region, wherein the second guard ring is separate from the first guard ring, wherein the third functional region is free of a guard ring; and a seal ring in the plurality of dielectric layers, wherein the seal ring encircles the first and the second guard rings, wherein the seal ring is separate from the first and the second guard rings.
 2. The IC device of claim 1, wherein the plurality of dielectric layers comprises metallization layers over the substrate.
 3. The IC device of claim 2, further comprising: one or more passivation layers over the metallization layers; and a conductive feature in the one or more passivation layers, wherein the conductive feature is over and connected to the seal ring, wherein a top surface of the conductive feature distal the substrate is further away from the substrate than a top surface of the first guard ring distal the substrate.
 4. The IC device of claim 1, wherein the first guard ring comprises a first conductive line in a first dielectric layer, a second conductive line in a second dielectric layer, and a first via bar in a third dielectric layer between the first and the second dielectric layers.
 5. The IC device of claim 4, wherein the first conductive line has a first width, and the first via bar has a second width smaller than the first width.
 6. The IC device of claim 4, wherein the first via bar is discontinuous, and at least one of the first conductive line and the second conductive line is discontinuous.
 7. The IC device of claim 6, further comprising a third conductive line extending through a discontinuous region of the first guard ring, wherein a first end of the third conductive line is inside the first guard ring, and a second end of the third conductive line is outside the first guard ring.
 8. The IC device of claim 7, wherein the third conductive line further extends into the second guard ring through a discontinuous region of the second guard ring.
 9. The IC device of claim 1, wherein the first functional region and the second functional region have different sizes or shapes.
 10. A method of manufacturing a semiconductor device, the method comprising: forming a plurality of integrated circuits (ICs) over a substrate; forming a plurality of seal rings in dielectric layers over the plurality of ICs, each of the plurality of seal rings surrounding a respective one of the plurality of ICs individually; forming a first guard ring in the dielectric layers, the first guard ring being inside a first seal ring of the plurality of seal rings and around a first functional region of a first IC of the plurality of the ICs; and forming a second guard ring in the dielectric layers, the second guard ring being inside the first seal ring and around a second functional region of the first IC, wherein the second guard ring is separate from the first guard ring, wherein a third functional region of the first IC does not have a guard ring around it, and wherein the first seal ring is separate from the first guard ring and the second guard ring.
 11. The method of claim 10, wherein the first guard ring is formed in a same processing step of a back-end-of-line (BEOL) manufacturing process as metal lines and vias in metallization layers over the first functional region of the first IC.
 12. The method of claim 10, wherein forming the first guard ring comprises forming alternating layers of conductive lines and via bars in the dielectric layers.
 13. The method of claim 12, wherein one of the via bars is formed to be discontinuous, and one of the conductive lines is formed to be discontinuous.
 14. The method of claim 10, wherein the forming the plurality of seal rings comprises forming the first seal ring around the first IC, wherein forming the first seal ring further comprises: forming a first ring around the first IC; and forming a second ring around the first ring, wherein the second ring is concentric with the first ring, wherein a width of the second ring is smaller than a width of the first ring.
 15. The method of claim 14, further comprising: forming one or more passivation layers over the dielectric layers; and forming a conductive feature in the one or more passivation layers, wherein the conductive feature is over and connected to the first ring.
 16. The method of claim 14, further comprising dicing along scribe lines between the plurality of ICs, wherein the second ring of the first seal ring is destroyed after the dicing, and the first ring of the first seal ring remains after the dicing.
 17. A method of manufacturing a semiconductor device, the method comprising: forming an integrated circuit (IC) die over a workpiece; forming a first guard ring in a material layer over the IC die, the first guard ring encircling a first functional region of the IC die; forming a second guard ring in the material layer, the second guard ring encircling a second functional region of the IC die, the second guard ring being spaced apart from the first guard ring, and a third functional region of the IC die being without a guard ring; and forming a seal ring in the material layer and along a perimeter of the IC die, the seal ring encircles the IC die individually and is spaced apart from the first guard ring and the second guard ring.
 18. The method of claim 17, wherein forming the first guard ring comprises forming conductive lines and via bars in the material layer, wherein the via bars of the first guard ring have a width smaller than a width of the conductive lines of the first guard ring.
 19. The method of claim 18, wherein the first guard ring is spaced apart from a perimeter of the first functional region by a distance of about 0.1 μm or less.
 20. The method of claim 18, wherein the forming the seal ring comprises forming two concentric rings in the material layer and around the IC die, wherein the method further comprises: dicing along a scribe line between the IC die and another IC die over the workpiece, wherein an outer ring of the two concentric rings of the seal ring is destroyed after the dicing, and an inner ring of the two concentric rings of the seal ring remains after the dicing. 